The orange juice challenge – we find out how visual cues can fool your taste buds

It’s January, time to look after ourselves, perhaps with a regular glass of orange juice. Research now shows that lots of environmental factors influence how we taste, and so, inspired by a piece of research published today in our journal Flavour, we decided to have a bit of fun in the office, and replicate an experiment all about tasty OJ.

The research by scientists at Nottingham and collaborators in Spain looked at whether the colour of orange juice affects our perception of sourness and sweetness. They added small amounts of red and green food colouring to orange juice so there were subtle changes, and used regular orange juice as a control to compare perception.

We repeated part of the study in the BioMed Central offices where our staff came and tasted orange juice to see if their perception was changed by the colouring we had added. It’s not an exact replication of the study, but is something fun you can try at home, and it gave us a chance to think about how to set up an experiment like those we publish in Flavour. Take a look at the video above to see how we got on!

Our results are shown below, and although we haven’t run any statistical analysis of significance, there are some trends. We found people rated the green orange juice as more sour when compared to red. It’s thought that green is perceived as sour because unripe fruit is usually green, and sour, so the brain associates the two. We also found an effect for the red food colouring, which was perceived as sweeter, when compared to both the control and the green juice. Red fruit is sweet and so again the brain makes this association.

Interestingly, the study published in Flavour didn’t find an effect on sweetness from the red juice, but we may have added more food colouring! We also found the our staff really disliked the green juice, even though the only difference was the colour.